Bill Bryson - A short history of nearly everything

Spring never came and summer never warmed: 1816 became known as the year without summer. Crops everywhere failed to grow. In Ireland a famine and associated typhoid epidemic killed sixty-five thousand people. In New England, the year became popularly known as Eighteen Hundred and Froze to Death. Morning frosts continued until June and almost no planted seed would grow. Short of fodder, livestock died or had to be prematurely slaughtered. In every way it was a dreadful year-almost certainly the worst for farmers in modern times. Yet globally the temperature fell by only about 1.5 degrees Fahrenheit. Earth’s natural thermostat, as scientists would learn, is an exceedingly delicate instrument.

The nineteenth century was already a chilly time. For two hundred years Europe and North America in particular had experienced a Little Ice Age, as it has become known, which permitted all kinds of wintry events-frost fairs on the Thames, ice-skating races along Dutch canals-that are mostly impossible now. It was a period, in other words, when frigidity was much on people’s minds. So we may perhaps excuse nineteenth-century geologists for being slow to realize that the world they lived in was in fact balmy compared with former epochs, and that much of the land around them had been shaped by crushing glaciers and cold that would wreck even a frost fair.

They knew there was something odd about the past. The European landscape was littered with inexplicable anomalies-the bones of arctic reindeer in the warm south of France, huge rocks stranded in improbable places-and they often came up with inventive but not terribly plausible explanations. One French naturalist named de Luc, trying to explain how granite boulders had come to rest high up on the limestone flanks of the Jura Mountains, suggested that perhaps they had been shot there by compressed air in caverns, like corks out of a popgun. The term for a displaced boulder is an erratic, but in the nineteenth century the expression seemed to apply more often to the theories than to the rocks.

The great British geologist Arthur Hallam has suggested that if James Hutton, the father of geology, had visited Switzerland, he would have seen at once the significance of the carved valleys, the polished striations, the telltale strand lines where rocks had been dumped, and the other abundant clues that point to passing ice sheets. Unfortunately, Hutton was not a traveler. But even with nothing better at his disposal than secondhand accounts, Hutton rejected out of hand the idea that huge boulders had been carried three thousand feet up mountainsides by floods-all the water in the world won’t make a boulder float, he pointed out-and became one of the first to argue for widespread glaciation. Unfortunately his ideas escaped notice, and for another half century most naturalists continued to insist that the gouges on rocks could be attributed to passing carts or even the scrape of hobnailed boots.

Local peasants, uncontaminated by scientific orthodoxy, knew better, however. The naturalist Jean de Charpentier told the story of how in 1834 he was walking along a country lane with a Swiss woodcutter when they got to talking about the rocks along the roadside. The woodcutter matter-of-factly told him that the boulders had come from the Grimsel, a zone of granite some distance away. “When I asked him how he thought that these stones had reached their location, he answered without hesitation: ‘The Grimsel glacier transported them on both sides of the valley, because that glacier extended in the past as far as the town of Bern.’ ”

Charpentier was delighted. He had come to such a view himself, but when he raised the notion at scientific gatherings, it was dismissed. One of Charpentier’s closest friends was another Swiss naturalist, Louis Agassiz, who after some initial skepticism came to embrace, and eventually all but appropriate, the theory.

Agassiz had studied under Cuvier in Paris and now held the post of Professor of Natural History at the College of Neuchâtel in Switzerland. Another friend of Agassiz’s, a botanist named Karl Schimper, was actually the first to coin the term ice age (in German Eiszeit ), in 1837, and to propose that there was good evidence to show that ice had once lain heavily across not just the Swiss Alps, but over much of Europe, Asia, and North America. It was a radical notion. He lent Agassiz his notes-then came very much to regret it as Agassiz increasingly got the credit for what Schimper felt, with some legitimacy, was his theory. Charpentier likewise ended up a bitter enemy of his old friend. Alexander von Humboldt, yet another friend, may have had Agassiz at least partly in mind when he observed that there are three stages in scientific discovery: first, people deny that it is true; then they deny that it is important; finally they credit the wrong person.

At all events, Agassiz made the field his own. In his quest to understand the dynamics of glaciation, he went everywhere-deep into dangerous crevasses and up to the summits of the craggiest Alpine peaks, often apparently unaware that he and his team were the first to climb them. Nearly everywhere Agassiz encountered an unyielding reluctance to accept his theories. Humboldt urged him to return to his area of real expertise, fossil fish, and give up this mad obsession with ice, but Agassiz was a man possessed by an idea.

Agassiz’s theory found even less support in Britain, where most naturalists had never seen a glacier and often couldn’t grasp the crushing forces that ice in bulk exerts. “Could scratches and polish just be due to ice ?” asked Roderick Murchison in a mocking tone at one meeting, evidently imagining the rocks as covered in a kind of light and glassy rime. To his dying day, he expressed the frankest incredulity at those “ice-mad” geologists who believed that glaciers could account for so much. William Hopkins, a Cambridge professor and leading member of the Geological Society, endorsed this view, arguing that the notion that ice could transport boulders presented “such obvious mechanical absurdities” as to make it unworthy of the society’s attention.

Undaunted, Agassiz traveled tirelessly to promote his theory. In 1840 he read a paper to a meeting of the British Association for the Advancement of Science in Glasgow at which he was openly criticized by the great Charles Lyell. The following year the Geological Society of Edinburgh passed a resolution conceding that there might be some general merit in the theory but that certainly none of it applied to Scotland.

Lyell did eventually come round. His moment of epiphany came when he realized that a moraine, or line of rocks, near his family estate in Scotland, which he had passed hundreds of times, could only be understood if one accepted that a glacier had dropped them there. But having become converted, Lyell then lost his nerve and backed off from public support of the Ice Age idea. It was a frustrating time for Agassiz. His marriage was breaking up, Schimper was hotly accusing him of the theft of his ideas, Charpentier wouldn’t speak to him, and the greatest living geologist offered support of only the most tepid and vacillating kind.

In 1846, Agassiz traveled to America to give a series of lectures and there at last found the esteem he craved. Harvard gave him a professorship and built him a first-rate museum, the Museum of Comparative Zoology. Doubtless it helped that he had settled in New England, where the long winters encouraged a certain sympathy for the idea of interminable periods of cold. It also helped that six years after his arrival the first scientific expedition to Greenland reported that nearly the whole of that semicontinent was covered in an ice sheet just like the ancient one imagined in Agassiz’s theory. At long last, his ideas began to find a real following. The one central defect of Agassiz’s theory was that his ice ages had no cause. But assistance was about to come from an unlikely quarter.